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how to use mcu to measure small ac voltage

2023/12/8 14:51:13

To measure small AC voltage using an MCU, you can follow these steps:

Choose an appropriate sensor: You need a sensor that can convert the AC voltage into a DC voltage that can be measured by the MCU. Some common sensors for this purpose are voltage dividers, transformers, and rectifiers.

Connect the sensor to the MCU: Once you have chosen the sensor, connect it to the MCU's input pins. The connection may vary depending on the sensor you choose, so refer to the datasheet or manufacturer's instructions for details.

Configure the MCU: Set up the MCU to read the sensor's output voltage. You may need to configure the analog-to-digital converter (ADC) and other parameters depending on your sensor and MCU.

Read the voltage: Use the MCU's code to continuously read the voltage from the sensor and process it as needed. You can display the voltage on an LCD or send it to a computer or other device for further analysis.

It's important to note that measuring voltage can be dangerous, especially if you're working with high voltages. Make sure to take proper safety precautions, such as wearing gloves and using a multimeter to verify the voltage before connecting it to the MCU.




2023/12/8 14:56:00

if the voltage is very small, like below 1 volt, how can I convert it to DC

2023/12/8 14:56:11

If the voltage you want to measure is below 1 volt, you may need to amplify it before converting it to DC. Here's a possible approach:

Amplify the AC voltage: Use an operational amplifier (op-amp) configured as a voltage amplifier to increase the voltage level of the AC signal. The choice of op-amp and the circuit configuration will depend on your specific requirements. An AC-coupled non-inverting amplifier or an instrumentation amplifier are common choices for amplifying small AC voltages.

Rectify the amplified signal: After amplification, the signal will still be an AC waveform. To convert it to DC, you can use a diode rectifier circuit. A simple half-wave rectifier or a full-wave rectifier can be used depending on your design constraints. This will result in a pulsating DC signal.

Smoothing the rectified signal: The pulsating DC signal can be further smoothed using a capacitor. Connect a capacitor in parallel to the output of the rectifier. The capacitor will charge when the rectified voltage is higher than its voltage level and discharge when the rectified voltage is lower. This smoothing process will reduce the ripple in the signal, resulting in a more stable DC voltage.

Measure the DC voltage: Connect the output of the smoothing capacitor to the MCU's input pin for measurement. Configure the ADC of the MCU to read the DC voltage level.

It's important to note that amplifying and rectifying small AC voltages can introduce noise and inaccuracies. Care should be taken in the circuit design to minimize these effects and ensure accurate measurements.
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